/**
 * \* Created with IntelliJ IDEA.
 * \* User: 冯若航
 * \* Date: 2021/5/31
 * \* Time: 22:51
 * \* To change this template use File | Settings | File Templates.
 * \* Description:
 * \
 */
public class 填充每个节点的下一个右侧节点指针 {
    class Node {
        public int val;
        public Node left;
        public Node right;
        public Node next;

        public Node() {}

        public Node(int _val) {
            val = _val;
        }

        public Node(int _val, Node _left, Node _right, Node _next) {
            val = _val;
            left = _left;
            right = _right;
            next = _next;
        }
    };

    public Node connect(Node root) {
        if(root==null){
            return root;
        }
        connectTwoNode(root.left,root.right);
        return root;
    }

    void connectTwoNode(Node node1,Node node2){
        if(node1==null||node2==null){
            return;
        }
        node1.next=node2;
        connectTwoNode(node1.left,node1.right);
        connectTwoNode(node2.left,node2.right);
        connectTwoNode(node1.right,node2.left);
    }
}